Hey guys, this is my first post. I have been making a set of moulds to make a carbon fibre wing skin. I started with cutting my pattern out of high density blue foam. I then coated it with a couple layers of coating epoxy with a few scoops of microbeads thrown in to make it thicker and sandable. After sanding it down to a nice smooth finish, I cleaned the surface with the Easy-Lease mold cleaner. I then applying several coats of Easy-Lease release agent (letting it dry for about 15 mins between coats). I then went ahead and applied the gelcoat for the uni-mould process. I put a second coat on after letting the first dry for a few hours. I then let it cure over night. The next morning these wrinkles appeared in the gelcoat right in the middle of the surface. I figured they were only on the exterior. I then proceeded with the coupling coat followed by the reinforcement. The next day when I pried the pattern out there were these worm holes where the wrinkles had been in the gelcoat. They appear to be air pockets but when I put the gelcoat down (both times) the was a generous even coat. I've been following the recomended ratios for the catalyst so I'm right stumped to figure out what I did wrong. I tried a second go using the same process but with waitng a little longer between the steps but I got the same wrinkles in the gelcoat again. Can you help me?

I think I am starting to notice, if your clay you use for making the mold has been used a few times before it seems to be more susceptible to worming or alligatoring. Must have something to do with the clay absorbing something.

Hey Don,

Where are you thinking clay is involved in this (do you mean the mould making putty? - if so, how can you use that a few times??)

I still wonder what would happen if I had moved faster with the two coats, giving only a couple hours between each, then going straight to the coupling coat on the same day. I read a post from a guy that did the whole thing in one day so I guess it would be worth a try. Maybe on a smaller part.                                                    

Hi Caden, Im glad the new attempt went much better. RE the above, I'm convinced it will go badly but give it a go for your own peace-of-mind and just to prove that undercuring is where the problem lies. A double application is favourable over a single so it's worth figuring it out. We get lots of feedback about how slow the Uni-Mould gelcoat is, especially at lower working tempertaures, so use the higher catalyst level and ensure plenty of cure time between coats to avoid the reaction.

--Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

i think what he means is modelling clay or wax used on the plug.  ie if hes reused the clay off an old plug, it may well pick up contaminates.